If you are not going to milk her then putting calves on her is the only option so that she doesn't get mastitis and you do not ruin her udder. I have several jersey/hol crosses that I use for nurse cows. You will not get anywhere near 80 lbs a day unless you feed her like she is on a commercial dairy. Most of the crosses will make about 3-4 gal a milking if being pushed for production. Most on the dairies that I test for only make 60-70 lbs avg a day at their peak. The cross does not get the best of both breeds. The butterfat will run closer to 3.8-4.1 % than the typical jersey at 4.2-4.5% or the holstein @ 3.3 - 3.7%. Many of them have udders that start to fall apart by the third or fourth lactation. The center ligament support does not hold up. This is not just based on a cow or two; this is years of seeing them on farms and having had many myself. But they do make good nurse cows if you have one with a good disposition.
So by all means put at least 2 more calves on her, most of mine will get a total of 4 calves if they are good in all 4 quarters, and they get grained 2x a day to help them reach their peak production.
Calves will not cause mastitis, the lack of getting milked out will cause mastitis and she could very easily get it bad enough to ruin a quarter or two.